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Homework Help: Physics lens homework

  1. Apr 19, 2007 #1
    1. The problem statement, all variables and given/known data

    A converging lens with a 50.0 mm focal length is used to focus an image of a very distant scene onto a flat screen 37.0 mm wide. What is the angular width of the scene included in the image on the screen?

    2. Relevant equations

    3. The attempt at a solution

    Basically I just did tan-1(37/50) = 36.5

    What are I doing wrong?
  2. jcsd
  3. Apr 19, 2007 #2


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    Gold Member

    Do you know how to calculate the height of the image as a function of it's distance form the lens? Use that to find get the distance and then use the distance and width to get the angle. Your problem is that you assumed that the distance was the focal length which isn't true.
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